CommandParser.hs

{-# LANGUAGE OverloadedStrings #-}

module CommandParser where
  import Data.Attoparsec.Char8
  import Control.Applicative
  import Data.ByteString

  data Command = Retrieve | Delete | New deriving Show

  parseCommand :: Parser Command
  parseCommand =
        (string "Retrieve"    >> return Retrieve)
    <|> (string "Delete"      >> return Delete)
    <|> (string "New"         >> return New)


  parseInput s = parseOnly $ parseCommand <|> string s

  parse :: ByteString -> Either String Command
  parse s = parseOnly parseCommand s